/* Partial correlation SSS estimation.
* Returns m0 and m1 estimates
*
* Source: "SSS Detection Method for Initial Cell Search in 3GPP LTE FDD/TDD Dual Mode Receiver"
* Jung-In Kim, Jung-Su Han, Hee-Jin Roh and Hyung-Jin Choi
*/
int srslte_sss_synch_m0m1_partial(srslte_sss_synch_t *q, cf_t *input, uint32_t M, cf_t ce[2*SRSLTE_SSS_N], uint32_t *m0, float *m0_value,
uint32_t *m1, float *m1_value)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL &&
m0 != NULL &&
m1 != NULL &&
M <= MAX_M)
{
cf_t y[2][SRSLTE_SSS_N];
extract_pair_sss(q, input, ce, y);
corr_all_sz_partial(y[0], q->fc_tables[q->N_id_2].s, M, q->corr_output_m0);
*m0 = srslte_vec_max_fi(q->corr_output_m0, SRSLTE_SSS_N);
if (m0_value) {
*m0_value = q->corr_output_m0[*m0];
}
srslte_vec_prod_cfc(y[1], q->fc_tables[q->N_id_2].z1[*m0], y[1], SRSLTE_SSS_N);
corr_all_sz_partial(y[1], q->fc_tables[q->N_id_2].s, M, q->corr_output_m1);
*m1 = srslte_vec_max_fi(q->corr_output_m1, SRSLTE_SSS_N);
if (m1_value) {
*m1_value = q->corr_output_m1[*m1];
}
ret = SRSLTE_SUCCESS;
}
return ret;
}
float compute_peak_sidelobe(srslte_pss_t *q, uint32_t corr_peak_pos, uint32_t conv_output_len)
{
// Find end of peak lobe to the right
int pl_ub = corr_peak_pos+1;
while(q->conv_output_avg[pl_ub+1] <= q->conv_output_avg[pl_ub] && pl_ub < conv_output_len) {
pl_ub ++;
}
// Find end of peak lobe to the left
int pl_lb;
if (corr_peak_pos > 2) {
pl_lb = corr_peak_pos-1;
while(q->conv_output_avg[pl_lb-1] <= q->conv_output_avg[pl_lb] && pl_lb > 1) {
pl_lb --;
}
} else {
pl_lb = 0;
}
int sl_distance_right = conv_output_len-1-pl_ub;
if (sl_distance_right < 0) {
sl_distance_right = 0;
}
int sl_distance_left = pl_lb;
int sl_right = pl_ub+srslte_vec_max_fi(&q->conv_output_avg[pl_ub], sl_distance_right);
int sl_left = srslte_vec_max_fi(q->conv_output_avg, sl_distance_left);
float side_lobe_value = SRSLTE_MAX(q->conv_output_avg[sl_right], q->conv_output_avg[sl_left]);
return q->conv_output_avg[corr_peak_pos]/side_lobe_value;
}
/* Differential SSS estimation.
* Returns m0 and m1 estimates
*
* Source: "SSS Detection Method for Initial Cell Search in 3GPP LTE FDD/TDD Dual Mode Receiver"
* Jung-In Kim, Jung-Su Han, Hee-Jin Roh and Hyung-Jin Choi
*
*/
int srslte_sss_synch_m0m1_diff_coh(srslte_sss_synch_t *q, cf_t *input, cf_t ce[2*SRSLTE_SSS_N], uint32_t *m0, float *m0_value,
uint32_t *m1, float *m1_value)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL &&
m0 != NULL &&
m1 != NULL)
{
cf_t yprod[SRSLTE_SSS_N];
cf_t y[2][SRSLTE_SSS_N];
extract_pair_sss(q, input, ce, y);
srslte_vec_prod_conj_ccc(&y[0][1], y[0], yprod, SRSLTE_SSS_N - 1);
corr_all_zs(yprod, q->fc_tables[q->N_id_2].sd, q->corr_output_m0);
*m0 = srslte_vec_max_fi(q->corr_output_m0, SRSLTE_SSS_N);
if (m0_value) {
*m0_value = q->corr_output_m0[*m0];
}
srslte_vec_prod_cfc(y[1], q->fc_tables[q->N_id_2].z1[*m0], y[1], SRSLTE_SSS_N);
srslte_vec_prod_conj_ccc(&y[1][1], y[1], yprod, SRSLTE_SSS_N - 1);
corr_all_zs(yprod, q->fc_tables[q->N_id_2].sd, q->corr_output_m1);
*m1 = srslte_vec_max_fi(q->corr_output_m1, SRSLTE_SSS_N);
if (m1_value) {
*m1_value = q->corr_output_m1[*m1];
}
ret = SRSLTE_SUCCESS;
}
return ret;
}
// TODO: Improve this implementation
void srslte_vec_norm_cfc(cf_t *x, float amplitude, cf_t *y, uint32_t len) {
// We should use fabs() here but is statistically should be similar
float *xp = (float*) x;
uint32_t idx = srslte_vec_max_fi(xp, 2*len);
float max = xp[idx];
// Normalize before TX
srslte_vec_sc_prod_cfc(x, amplitude/max, y, len);
}
/** Performs time-domain PSS correlation.
* Returns the index of the PSS correlation peak in a subframe.
* The frame starts at corr_peak_pos-subframe_size/2.
* The value of the correlation is stored in corr_peak_value.
*
* Input buffer must be subframe_size long.
*/
int srslte_pss_synch_find_pss(srslte_pss_synch_t *q, cf_t *input, float *corr_peak_value)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL)
{
uint32_t corr_peak_pos;
uint32_t conv_output_len;
if (!srslte_N_id_2_isvalid(q->N_id_2)) {
fprintf(stderr, "Error finding PSS peak, Must set N_id_2 first\n");
return SRSLTE_ERROR;
}
/* Correlate input with PSS sequence */
if (q->frame_size >= q->fft_size) {
#ifdef CONVOLUTION_FFT
memcpy(q->tmp_input, input, q->frame_size * sizeof(cf_t));
conv_output_len = srslte_conv_fft_cc_run(&q->conv_fft, q->tmp_input, q->pss_signal_time[q->N_id_2], q->conv_output);
#else
conv_output_len = srslte_conv_cc(input, q->pss_signal_time[q->N_id_2], q->conv_output, q->frame_size, q->fft_size);
#endif
} else {
for (int i=0;i<q->frame_size;i++) {
q->conv_output[i] = srslte_vec_dot_prod_ccc(q->pss_signal_time[q->N_id_2], &input[i], q->fft_size);
}
conv_output_len = q->frame_size;
}
#ifdef SRSLTE_PSS_ABS_SQUARE
srslte_vec_abs_square_cf(q->conv_output, q->conv_output_abs, conv_output_len-1);
#else
srslte_vec_abs_cf(q->conv_output, q->conv_output_abs, conv_output_len-1);
#endif
srslte_vec_sc_prod_fff(q->conv_output_abs, q->ema_alpha, q->conv_output_abs, conv_output_len-1);
srslte_vec_sc_prod_fff(q->conv_output_avg, 1-q->ema_alpha, q->conv_output_avg, conv_output_len-1);
srslte_vec_sum_fff(q->conv_output_abs, q->conv_output_avg, q->conv_output_avg, conv_output_len-1);
/* Find maximum of the absolute value of the correlation */
corr_peak_pos = srslte_vec_max_fi(q->conv_output_avg, conv_output_len-1);
// save absolute value
q->peak_value = q->conv_output_avg[corr_peak_pos];
#ifdef SRSLTE_PSS_RETURN_PSR
// Find second side lobe
// Find end of peak lobe to the right
int pl_ub = corr_peak_pos+1;
while(q->conv_output_avg[pl_ub+1] <= q->conv_output_avg[pl_ub] && pl_ub < conv_output_len) {
pl_ub ++;
}
// Find end of peak lobe to the left
int pl_lb;
if (corr_peak_pos > 2) {
pl_lb = corr_peak_pos-1;
while(q->conv_output_avg[pl_lb-1] <= q->conv_output_avg[pl_lb] && pl_lb > 1) {
pl_lb --;
}
} else {
pl_lb = 0;
}
int sl_distance_right = conv_output_len-1-pl_ub;
if (sl_distance_right < 0) {
sl_distance_right = 0;
}
int sl_distance_left = pl_lb;
int sl_right = pl_ub+srslte_vec_max_fi(&q->conv_output_avg[pl_ub], sl_distance_right);
int sl_left = srslte_vec_max_fi(q->conv_output_avg, sl_distance_left);
float side_lobe_value = SRSLTE_MAX(q->conv_output_avg[sl_right], q->conv_output_avg[sl_left]);
if (corr_peak_value) {
*corr_peak_value = q->conv_output_avg[corr_peak_pos]/side_lobe_value;
DEBUG("peak_pos=%2d, pl_ub=%2d, pl_lb=%2d, sl_right: %2d, sl_left: %2d, PSR: %.2f/%.2f=%.2f\n", corr_peak_pos, pl_ub, pl_lb,
sl_right,sl_left, q->conv_output_avg[corr_peak_pos], side_lobe_value,*corr_peak_value);
}
#else
if (corr_peak_value) {
*corr_peak_value = q->conv_output_avg[corr_peak_pos];
}
#endif
if (q->frame_size >= q->fft_size) {
ret = (int) corr_peak_pos;
} else {
ret = (int) corr_peak_pos + q->fft_size;
}
}
return ret;
}
/** Performs time-domain PSS correlation.
* Returns the index of the PSS correlation peak in a subframe.
* The frame starts at corr_peak_pos-subframe_size/2.
* The value of the correlation is stored in corr_peak_value.
*
* Input buffer must be subframe_size long.
*/
int srslte_pss_find_pss(srslte_pss_t *q, const cf_t *input, float *corr_peak_value)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL)
{
uint32_t corr_peak_pos;
uint32_t conv_output_len;
if (!srslte_N_id_2_isvalid(q->N_id_2)) {
ERROR("Error finding PSS peak, Must set N_id_2 first\n");
return SRSLTE_ERROR;
}
/* Correlate input with PSS sequence
*
* We do not reverse time-domain PSS signal because it's conjugate is symmetric.
* The conjugate operation on pss_signal_time has been done in srslte_pss_init_N_id_2
* This is why we can use FFT-based convolution
*/
if (q->frame_size >= q->fft_size) {
#ifdef CONVOLUTION_FFT
memcpy(q->tmp_input, input, (q->frame_size * q->decimate) * sizeof(cf_t));
if(q->decimate > 1) {
srslte_filt_decim_cc_execute(&(q->filter), q->tmp_input, q->filter.downsampled_input, q->filter.filter_output , (q->frame_size * q->decimate));
conv_output_len = srslte_conv_fft_cc_run_opt(&q->conv_fft, q->filter.filter_output,q->pss_signal_freq_full[q->N_id_2], q->conv_output);
} else {
conv_output_len = srslte_conv_fft_cc_run_opt(&q->conv_fft, q->tmp_input, q->pss_signal_freq_full[q->N_id_2], q->conv_output);
}
#else
conv_output_len = srslte_conv_cc(input, q->pss_signal_time[q->N_id_2], q->conv_output, q->frame_size, q->fft_size);
#endif
} else {
for (int i=0;i<q->frame_size;i++) {
q->conv_output[i] = srslte_vec_dot_prod_ccc(q->pss_signal_time[q->N_id_2], &input[i], q->fft_size);
}
conv_output_len = q->frame_size;
}
// Compute modulus square
srslte_vec_abs_square_cf(q->conv_output, q->conv_output_abs, conv_output_len-1);
// If enabled, average the absolute value from previous calls
if (q->ema_alpha < 1.0 && q->ema_alpha > 0.0) {
srslte_vec_sc_prod_fff(q->conv_output_abs, q->ema_alpha, q->conv_output_abs, conv_output_len-1);
srslte_vec_sc_prod_fff(q->conv_output_avg, 1-q->ema_alpha, q->conv_output_avg, conv_output_len-1);
srslte_vec_sum_fff(q->conv_output_abs, q->conv_output_avg, q->conv_output_avg, conv_output_len-1);
} else {
memcpy(q->conv_output_avg, q->conv_output_abs, sizeof(float)*(conv_output_len-1));
}
/* Find maximum of the absolute value of the correlation */
corr_peak_pos = srslte_vec_max_fi(q->conv_output_avg, conv_output_len-1);
// save absolute value
q->peak_value = q->conv_output_avg[corr_peak_pos];
#ifdef SRSLTE_PSS_RETURN_PSR
if (corr_peak_value) {
*corr_peak_value = compute_peak_sidelobe(q, corr_peak_pos, conv_output_len);
}
#else
if (corr_peak_value) {
*corr_peak_value = q->conv_output_avg[corr_peak_pos];
}
#endif
if(q->decimate >1) {
int decimation_correction = (q->filter.num_taps - 2);
corr_peak_pos = corr_peak_pos - decimation_correction;
corr_peak_pos = corr_peak_pos*q->decimate;
}
if (q->frame_size >= q->fft_size) {
ret = (int) corr_peak_pos;
} else {
ret = (int) corr_peak_pos + q->fft_size;
}
}
return ret;
}
void srslte_agc_process(srslte_agc_t *q, cf_t *signal, uint32_t len) {
float gain_db = 10*log10(q->gain);
float gain_uhd_db = 1.0;
//float gain_uhd = 1.0;
float y = 0;
// Apply current gain to input signal
if (!q->uhd_handler) {
srslte_vec_sc_prod_cfc(signal, q->gain, signal, len);
} else {
if (q->gain < 1) {
q->gain = 1.0;
}
if (isinf(gain_db) || isnan(gain_db)) {
q->gain = 10.0;
} else {
gain_uhd_db = q->set_gain_callback(q->uhd_handler, gain_db);
q->gain = pow(10, gain_uhd_db/10);
}
}
float *t;
switch(q->mode) {
case SRSLTE_AGC_MODE_ENERGY:
y = sqrtf(crealf(srslte_vec_dot_prod_conj_ccc(signal, signal, len))/len);
break;
case SRSLTE_AGC_MODE_PEAK_AMPLITUDE:
t = (float*) signal;
y = t[srslte_vec_max_fi(t, 2*len)];// take only positive max to avoid abs() (should be similar)
break;
default:
fprintf(stderr, "Unsupported AGC mode\n");
return;
}
if (q->nof_frames > 0) {
q->y_tmp[q->frame_cnt++] = y;
if (q->frame_cnt == q->nof_frames) {
q->frame_cnt = 0;
switch(q->mode) {
case SRSLTE_AGC_MODE_ENERGY:
y = srslte_vec_acc_ff(q->y_tmp, q->nof_frames)/q->nof_frames;
break;
case SRSLTE_AGC_MODE_PEAK_AMPLITUDE:
y = q->y_tmp[srslte_vec_max_fi(q->y_tmp, q->nof_frames)];
break;
default:
fprintf(stderr, "Unsupported AGC mode\n");
return;
}
}
}
double gg = 1.0;
if (q->isfirst) {
q->y_out = y;
q->isfirst = false;
} else {
if (q->frame_cnt == 0) {
q->y_out = (1-q->bandwidth) * q->y_out + q->bandwidth * y;
if (!q->lock) {
gg = expf(-0.5*q->bandwidth*logf(q->y_out/q->target));
q->gain *= gg;
}
INFO("AGC gain: %.2f (%.2f) y_out=%.3f, y=%.3f target=%.1f gg=%.2f\n", gain_db, gain_uhd_db, q->y_out, y, q->target, gg);
}
}
}
static int srslte_pdsch_codeword_decode(srslte_pdsch_t *q, srslte_pdsch_cfg_t *cfg,
srslte_softbuffer_rx_t *softbuffer, uint16_t rnti, uint8_t *data,
uint32_t codeword_idx, uint32_t tb_idx, bool *ack) {
srslte_ra_nbits_t *nbits = &cfg->nbits[tb_idx];
srslte_ra_mcs_t *mcs = &cfg->grant.mcs[tb_idx];
uint32_t rv = cfg->rv[tb_idx];
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (softbuffer && data && ack) {
INFO("Decoding PDSCH SF: %d (CW%d -> TB%d), Mod %s, NofBits: %d, NofSymbols: %d, NofBitsE: %d, rv_idx: %d\n",
cfg->sf_idx, codeword_idx, tb_idx, srslte_mod_string(mcs->mod), mcs->tbs,
nbits->nof_re, nbits->nof_bits, rv);
/* demodulate symbols
* The MAX-log-MAP algorithm used in turbo decoding is unsensitive to SNR estimation,
* thus we don't need tot set it in the LLRs normalization
*/
srslte_demod_soft_demodulate_s(mcs->mod, q->d[codeword_idx], q->e[codeword_idx], nbits->nof_re);
/* Select scrambling sequence */
srslte_sequence_t *seq = get_user_sequence(q, rnti, codeword_idx, cfg->sf_idx, nbits->nof_bits);
/* Bit scrambling */
srslte_scrambling_s_offset(seq, q->e[codeword_idx], 0, nbits->nof_bits);
uint32_t qm = nbits->nof_bits/nbits->nof_re;
switch(cfg->grant.mcs[tb_idx].mod) {
case SRSLTE_MOD_BPSK:
qm = 1;
break;
case SRSLTE_MOD_QPSK:
qm = 2;
break;
case SRSLTE_MOD_16QAM:
qm = 4;
break;
case SRSLTE_MOD_64QAM:
qm = 6;
break;
default:
ERROR("No modulation");
}
int16_t *e = q->e[codeword_idx];
if (q->csi_enabled) {
const uint32_t csi_max_idx = srslte_vec_max_fi(q->csi[codeword_idx], nbits->nof_bits / qm);
float csi_max = 1.0f;
if (csi_max_idx < nbits->nof_bits / qm) {
csi_max = q->csi[codeword_idx][csi_max_idx];
}
for (int i = 0; i < nbits->nof_bits / qm; i++) {
const float csi = q->csi[codeword_idx][i] / csi_max;
for (int k = 0; k < qm; k++) {
e[qm * i + k] = (int16_t) ((float) e[qm * i + k] * csi);
}
}
}
/* Return */
ret = srslte_dlsch_decode2(&q->dl_sch, cfg, softbuffer, q->e[codeword_idx], data, tb_idx);
q->last_nof_iterations[codeword_idx] = srslte_sch_last_noi(&q->dl_sch);
if (ret == SRSLTE_SUCCESS) {
*ack = true;
} else if (ret == SRSLTE_ERROR) {
*ack = false;
ret = SRSLTE_SUCCESS;
} else if (ret == SRSLTE_ERROR_INVALID_INPUTS) {
*ack = false;
ret = SRSLTE_ERROR;
}
} else {
ERROR("Detected NULL pointer in TB%d &softbuffer=%p &data=%p &ack=%p", codeword_idx, softbuffer, (void*)data, ack);
}
return ret;
}